German 41 07 480 describes a pedicle screw which serves for anchoring implants in the spinal column to which end bores are formed in the pedicle of the vertebra in which the threaded shaft of a pedicle screw is threaded. This type of mounting of implants has shown itself effective in practice; however cases are known in which anatomical considerations exclude the use of a pedicle screw, for instance with anomalies or with such bone structures that do not allow the use of a screw.
It is known to use, as an alternative to a pedicle screw, hooks that are hung on the pedicle or on the lamina of the spinal column in order to effect a distraction or compression. Since the hooks are only secured at one arm, the result is in many cases an insecure mounting.